Band 116, Heft 9

The annealing temperature, its duration and quenching rate may play a significant role in tuning the functional properties of high entropy alloys (HEAs). In the present work, Co 35 Fe 10 Ni 30 Ti 20 Al 5 HEA is investigated for the effect of different quenching rates on the phase evolution and magnetic properties. The Co 35 Fe 10 Ni 30 Ti 20 Al 5 HEA was synthesized through mechanical alloying and subsequently annealed at 700 °C for 2 h followed by quenching through different rates-furnace cooled, room temperature (RT-) cooled, ice-bath quenched and liquid-N 2 quenched separately. The as-synthesized sample exhibited a mixture of fcc, bcc and a slight content of R-phase. The synthesized phase was found to be maintained after quenching at different rates. The magnetic behavior measured for different samples confirmed the characteristic ferromagnetic nature having coercivity in the range of semi-hard magnetic material. We found variation in the volume phase fraction of the secondary bcc phase and the value of coercivity with the variation of the quenching rate. This study may provide an appropriate idea of the quenching rate for tuning the magnetic property of HEAs.

Gadolinium (10 %)-modified bismuth nickel titanate (BNTO) ceramic, was synthesized by a solid-state reaction method. The as-synthesized ceramic was calcined at a temperature of 900 °C. The current work shows the synthesis, structural and dielectric characteristics of (Bi 0.9 Gd 0.1 )(Ni 0.5 Ti 0.5 )O 3 ceramic. Further characteristics were investigated using analytical tools such as X-ray diffraction and a phase-sensitive meter. The surface morphology of the ceramic compound was confirmed through scanning electron microscope analysis. Energy-dispersive X-ray analysis confirms the purity of the sample with an equivalent amount of weight and atomic percentage. The dielectric and impedance properties of ceramic were analyzed by computing the dielectric response over a selected range of frequency and temperature. The P–E loop tracer was used to study the ferroelectric nature of the sample. Based on the enhancement of its electrical properties, this ceramic may be useful for various electronic applications.

Bacterial cellulose is a renewable biomacromolecule with significant environmental benefits over plant cellulose. It is secreted extracellularly by several bacterial species, including Gram-positive Sarcina ventriculi and Gram-negative bacteria such as Gluconacetobacter , Agrobacterium , and Acetobacter . Because of its remarkable physicochemical properties, BC has emerged as an excellent polymer with wide application domains in both industrial as well as biomedical fields. In our study, we investigated the potential of Acetobacter aceti MTCC 2623 for BC production under static conditions and evaluated the impact of incubation temperature, pH, and carbon sources on BC production. The maximum BC yield obtained was 4.18 ± 0.19 g L −1 by A . aceti under static conditions using 2 % w/v glucose as a carbon source, at 30 °C and pH 6.0. The BC samples produced were analyzed for physicochemical properties using Fourier transform infrared spectroscopy and differential scanning calorimetry, providing detailed insights into their structural composition and heat stability. X-ray diffraction indicates the crystallinity and amorphous regions. Fourier transform infrared spectroscopy analysis revealed that all BC samples were crystalline and exhibited variations in crystallinity ratios compared to commercial cellulose.

Polycrystalline pellets of Bi 1·75 Pb 0·35 Sr 2- x La x Ca 2 Cu 3 O 10 ( x = 0.00, 0.02, 0.06, 0.08) have been synthesized using a solid-state reaction technique. The structural characterization carried out by X-ray diffraction confirms tetragonal phase and a shift in peak positions due to incorporation of La at Sr sites. Scanning electron micrographs reveal a decrease in grain size with La doping. The electrical resistivity data indicate a superconducting transition at about 106 K for pristine (Bi, Pb)-2223 pellet which is suppressed on La doping in Bi 1·75 Pb 0·35 Sr 2- x La x Ca 2 Cu 3 O 10 . Apart from that an increase in resistivity and metallic to semiconducting transition has also been observed at higher La concentration (for x = 0.08). Hole-type conduction has been confirmed for each sample through thermopower measurement. The thermopower of investigated pellets has been explained in the light of various theoretical models and correlations as a function of temperature. Amongst them, the Mott–Jones model provides a satisfactory explanation of experimental result. An improvement in power factor of Bi 1·75 Pb 0·35 Sr 2- x La x Ca 2 Cu 3 O 10 doped with 8 wt.% of La has been observed in a specific temperature range which indicates that thermoelectric performance may be improved by optimizing La concentration.

The present study demonstrates the feasibility of synthesizing high-quality ZnO nanostructures at extremely low temperatures using the sol–gel method. The synthesized nanostructured samples are analysed through various analytical techniques such as X-ray diffraction, UV–Vis spectroscopy, field emission scanning electron microscopy, and zeta potential measurements. The X-ray diffraction analysis revealed highly intense, distinct peaks corresponding to the (100) (002), and (101) crystallographic planes, confirming the presence of a hexagonal wurtzite structure for all synthesized samples. All the samples exhibited maximum absorption peaks at wavelengths of 383 nm, 368 nm, and 358 nm, with corresponding band gap energies 2.93 eV, 3.58 eV, and 3.68 eV. The field effect scanning electron microscopy analysis revealed that the synthesized samples (1) (II), and (III) displayed a microstructure like a nanoparticle. Furthermore, zeta potential measurements provided insights into the surface charge characteristics of the samples. This approach can lead to the development of cost-effective, energy-efficient, and scalable processes for the fabrication of advanced materials and devices in optoelectronics, sensors, catalysis, and biomedical applications. Further research is needed to optimize the synthesis parameters and explore the full potential of these low-temperature-synthesized ZnO nanostructures in various applications.

During the last few years, nanomaterials have sparked a lot of attention due to their properties. Therefore the fundamental goal of this paper, we analyze the impact of sintering temperature (450–750) °C on structural, optical properties, and magnetoresistance of tin oxide nanomaterial via the co-precipitation method. X-ray diffraction and RAMAN reveal a tetragonal crystal structure without the presence of any impurities. Further, we found the growth of crystallinity with higher sintering temperatures of pellets. The morphology studies reveal the inhomogeneity of particles and they are closely packed together. UV–Vis spectroscopy results show that tuning the bandgap suggested the improvement of optical properties in tin oxide in the role of optoelectronic devices, sensors, etc. We found a reduction in resistivity ( ρ ) and an increment in magnetoresistance as the sintering temperature of pellets rises.

Crystal structure, surface morphology, dielectric and electrical characterisation of manganese and gadolinium co-modified barium strontium titanate (BST) composite is reported. In the present work, Mn and Gd co-modified BST, i.e. Ba 0.76 (Gd 0.5 Mn 0.5 )0.04 Sr 0.2 TiO 3 composite is synthesised by sol-gel reaction technique. The crystallographic phase formation of calcined powder is confirmed by the X-ray diffraction technique. Unit cell parameters are extracted from Rietveld refinement of the XRD data using X’Pert High-score plus software. Average crystallite size and lattice strain are estimated from full-width half maxima of diffraction peaks following Scherrer’s equation and Haldar–Wagner’s method. The dielectric and electrical investigations are carried out by measuring the dielectric constant on the sintered pellets as a function of temperature from room temperature to 300 °C at the AC field frequencies of 100 Hz – 1 MHz.

As the technology of membrane-based fuel cells has advanced quickly, there has been a surge in demand for clean, sustainable energy applications worldwide. Raising the proton exchange membrane fuel cell (PEMFC) power density is one of the most important infrastructure and device-level issues that must be resolved before widespread commercialization can occur, and aggressive targets have been put forth internationally. Polymeric membranes have attained significant attention within the realm of energy generation and conversion systems. This is attributed not only to their favorable economic considerations but also to the ease of synthesis, rendering them particularly compelling for the research community. However, the effective design of membrane materials is imperative to their successful integration into respective systems. Grafting of monomers onto prepolymers has been an excellent surface modification methodology to create desired functionalities for polymers. Hydrocarbon polymers are not so well studied in the literature, especially LLDPE. The lifespan and performance of proton exchange membrane fuel cells are determined by two opposite characteristics of proton-conductive membranes which are challenging to achieve simultaneously. Herein, we developed a novel solid polymer electrolyte membrane through the combination of vinyl heterocyclic monomers and polyethylene as backbone. Because of the right combination, hydrophilic monomers; 1-vinylimidazole and 4-vinylpyridine and hydrophobic backbone-LLDPE the resulting composite membrane [LLDPE-g-P(1VIm/4VP)] showed fair basic qualities, in terms of ion exchange capacity and water uptake calculations. All synthesized membranes showed dehydration after 90 °C signifying the optimal range of membranes for electrochemical applications.

This study entails the synthesis and characterization of palladium complexes containing N-(benzothiazol-2-yl)benzamide (LH) along with various hybrid ligands, including 2-aminopyridine (2amp), 4-aminopyridine (4amp), phenanthroline (Phen), triphenylphosphine (PPh 3 ), as well as diphosphines such as dppp and dppb. Characterization of the prepared complexes was performed using molar conductivity analyses, FTIR, 31 P-NMR, 1 H-NMR, and 13 C-NMR spectra. The proposed geometry around the metal ion is mostly planar, with the LH bond acting as a bidentate bond via the N atom of the pentameric ring in the benzothiazole and the O atom of the carbonyl group. The hydrogen storage capacities of selected complexes were evaluated under high pressure using the VTI/HPVA method. The results indicate that all complexes studied exhibit hydrogen storage capacity, with the highest storage values observed in [Pd(LH)(4amp) 2 ]Cl 2 , [Pd(LH)(dppb)]Cl 2 , and [Pd(LH)(PPh 3 )Cl]Cl complexes reach 471, 212, 166 mL g −1 , respectively.

This study reports the deposition of compact TiO 2 (c-TiO 2 ) thin films, which serve as seed layers for the growth of TiO 2 nanostructures. Five samples, labeled S 1 , S 2 , S 3 , S 4 , and S 5 , were prepared with 2, 4, 6, 8, and 10 deposition cycles of c-TiO 2 thin films, respectively. Using the hydrothermal method, rod-like TiO 2 nanostructures were successfully grown on these thin films. Field emission scanning electron microscopy images confirmed the formation of rod-like nanostructures with an average length of approximately 0.7 μm, and the number density of the nanorods increased with the seed layer thickness. X-ray diffraction analysis revealed the presence of both anatase and rutile phases of TiO 2 , with the majority of peaks corresponding to the anatase phase. The UV–Vis transmittance ranged from 60–90 % in the 400–700 nm wavelength range for all five films. The optical band gaps for samples S 1 , S 2 , S 3 , S 4 , and S 5 were 3.11, 3.10, 3.07, 3.05, and 3.05 eV, respectively. Based on the overall characterizations, sample S 2 demonstrated the best properties. This study indicates that the TiO 2 nanorod layer on the c-TiO 2 seed layer effectively enhances the electron transport performance of perovskite-based photovoltaic devices.